The effect of SiC co-deposition on the oxidation behavior of Carbon/Carbon composites prepared by chemical vapor deposition

Abstract

The effects of SiC codeposition on the oxidation kinetics and oxidized surface morphology of carbon/carbon composites prepared by chemical vapor deposition have been investigated in the temperature range 600 to 1350-degrees-C in air. The oxidation rate of SiC-codeposited C/C composites is slower than that of SiC-free C/C composites below 800- degrees-C. However, the C/C composites have nearly the same apparent activation energies for oxidation, regardless of SiC codeposition. It is suggested that SiC particles in C/C composites affect the growth of oxidized pits, not the oxidation mechanism of the composites. The SiC particles are unable to act as an oxygen diffusion barrier, so the oxidation of C/C composites is not retarded by SiC particles above 800-degrees-C. SiC particles react with oxygen to produce glassy SiO2 and join to form a skeleton of the initial fiber mat after full oxidation above 1000-degrees-C.